Search

Riemerella anatipestifer is an important bacterial pathogen in poultry. Pathogenic bacteria recruit host complement factors to resist the bactericidal effect of serum complement. Vitronectin (Vn) is a complementary regulatory protein that inhibits the formation of the membrane attack complex (MAC). Microbes use outer membrane proteins (OMPs) to hijack Vn for complement evasion. However, the mechanism by which R. anatipestifer achieves evasion is unclear. This study aimed to characterise OMPs of R. anatipestifer which interact with duck Vn (dVn) during complement evasion. Far-western assays and comparison of wild-type and mutant strains that were treated with dVn and duck serum demonstrated particularly strong binding of OMP76 to dVn. These data were confirmed with Escherichia coli strains expressing and not expressing OMP76. Combining tertiary structure analysis and homology modelling, truncated and knocked-out fragments of OMP76 showed that a cluster of critical amino acids in an extracellular loop of OMP76 mediate the interaction with dVn. Moreover, binding of dVn to R. anatipestifer inhibited MAC deposition on the bacterial surface thereby enhancing survival in duck serum. Virulence of the mutant strain ΔOMP76 was attenuated significantly relative to the wild-type strain. Furthermore, adhesion and invasion abilities of ΔOMP76 decreased, and histopathological changes showed that ΔOMP76 was less virulent in ducklings. Thus, OMP76 is a key virulence factor of R. anatipestifer. The identification of OMP76-mediated evasion of complement by recruitment of dVn contributes significantly to the understanding of the molecular mechanism by which R. anatipestifer escapes host innate immunity and provides a new target for the development of subunit vaccines.

Grain weight is a major determinant in rice yield, which is tightly associated with grain size. However, the underlying molecular mechanisms that control this trait remain unclear. Here, we report a rice (Oryza sativa) mutant, low grain weight (lgw), which shows that reduced grain length is caused by decreased cell elongation and proliferation. Map-based cloning revealed that all mutant phenotypes resulted from a nine-base pair (bp) deletion in LGW, which encodes the kinesin-like protein BRITTLE CULM12 (BC12). Protein sequence alignment analysis revealed that the mutation site was located at the nuclear localization signal (NLS) of LGW/BC12, resulting in the lgw protein not being located in the nucleus. LGW is preferentially expressed in both culms and roots, as well as in the early developing panicles. Overexpression of LGW increased the grain length, indicating that LGW is a positive regulator for regulating grain length. In addition, LGW/BC12 is directly bound to the promoter of GW7 and activates its expression. Elevating the GW7 expression levels in lgw plants rescued the small grain size phenotype. We conclude that LGW regulates grain development by directly binding to the GW7 promoter and activating its expression. Our findings revealed that LGW plays an important role in regulating grain size, and manipulation of this gene provides a new strategy for regulating grain weight in rice.

Additional file 9: Table S1 Cell wall composition analysis of internodes of wild type and cef3-c1 plants.

Additional file 1: Table S1. Primer information and sequences.

The fault of electrode line can pose serious threat to the safe and stable operation of the High Voltage Direct Current (HVDC) system, but it is quite difficult to detect the line fault by normal ways because the grounding electrode line is usually at ground potential. This paper presents a novel fault monitoring and location system for HVDC electrode line, which is based on the TDR technique and specially designed according to the characteristics of electrode line. The system injects differential mode voltage pulse to monitor the electrode line, and reduces the cancellation of differential mode signal through series reactance. Theoretically, this system is immune to the interference signal from the HVDC system, and can greatly improve the Signal-to-Noise Ratio (SNR) of the reflected pulse. In addition, the system uses a waveform comparison algorithm to solve the problem of line parameter uniform and slowly changing, which could make much trouble to the normal TDR methods. For this fault monitoring and location system, the output pulse amplitude is designed as up to 500 V, the pulse width range is about 1-5 $\mu$s, and the pulse sampling rate is as high as 10 MHz. Simulation results and field applications show that this system can achieve excellent fault monitoring and location result for the HVDC electrode line, with the fault location accuracy better than 300m.

Analyzing the spatio-temporal characteristics and identifying of main factors that drive grassland degradation are essential for formulating ecological restoration measures for grassland. In this study, we addressed two main scientific questions: (1) how to accurately characterize the spatial and temporal variability in grassland degradation; and (2) how to identify the dominant factors that affect grassland degradation. Based on the data obtained from 270 field sampling points (912 quadrats) and MODIS, we selected the temperature vegetation dryness index (TVDI), vegetation coverage (VC), biomass and ecosystem service values (ESVs) to study the degradation of grassland in Altay Prefecture, China. From 2000 to 2016, the area with decrease in TVDI accounted for 93.4% of the total grassland. The VC values in the warm steppe and mountain meadow areas decreased by 5.3% and 1.6%, respectively, and the biomass decreased by 80% and 76.4% in these areas. Compared with 2000–2005, the mean total ESVs decreased by 5.1% in 2011–2016, where the reductions in the ESVs for warm steppe and mountain meadow accounted for 54.3% and 38% of the total reduction, respectively. The results showed that the degradation trends were more significant in the warm steppe and mountain meadow than the other land types. These findings improve our understanding of the spatial heterogeneity of grassland degradation. Human disturbance was the main factor responsible for grassland degradation in Altay Prefecture, according to the framework developed in this study based on biomass and TVDI metrics. Our results provide a reference for characterizing the spatio-temporal variability of grassland degradation by combining statistical and spatial analyses, as well as a simple framework for application in similar regions to analyze the effects of climate change and human disturbance on grassland degradation. Keywords: Grassland degradation, Biomass, Ecosystem service values, TVDI, Human activities, Altay

BackgroundThe Greater Mekong Subregion is aiming to achieve regional malaria elimination by 2030. Though a shift in malaria parasite species predominance by Plasmodium vivax has been recently documented, the transmission of the two minor Plasmodium species, Plasmodium malariae and Plasmodium ovale spp., is poorly characterized in the region. This study aims to determine the prevalence of these minor species in the China-Myanmar border area and their genetic diversity.MethodsEpidemiology study was conducted during passive case detection in hospitals and clinics in Myanmar and four counties in China along the China-Myanmar border. Cross-sectional surveys were conducted in villages and camps for internally displaced persons to determine the prevalence of malaria infections. Malaria infections were diagnosed initially by microscopy and later in the laboratory using nested PCR for the SSU rRNA genes. Plasmodium malariae and P. ovale infections were confirmed by sequencing the PCR products. The P. ovale subtypes were determined by sequencing the Pocytb, Pocox1 and Pog3p genes. Parasite populations were evaluated by PCR amplification and sequencing of the MSP-1 genes. Antifolate sensitivity was assessed by sequencing the dhfr-ts and dhps genes from the P. malariae and P. ovale isolates.ResultsAnalysis of 2701 blood samples collected from the China-Myanmar border by nested PCR targeting the parasite SSU rRNA genes identified 561 malaria cases, including 161 Plasmodium falciparum, 327 P. vivax, 66 P. falciparum/P. vivax mixed infections, 4 P. malariae and 3 P. ovale spp. P. vivax and P. falciparum accounted for >60 and ~30% of all malaria cases, respectively. In comparison, the prevalence of P. malariae and P. ovale spp. was very low and only made up ~1% of all PCR-positive cases. Nevertheless, these two species were often misidentified as P. vivax infections or completely missed by microscopy even among symptomatic patients. Phylogenetic analysis of the SSU rRNA, Pocytb, Pocox1 and Pog3p genes confirmed that the three P. ovale spp. isolates belonged to the subtype P. ovale curtisi. Low-level genetic diversity was detected in the MSP-1, dhfr and dhps genes of these minor parasite species, potentially stemming from the low prevalence of these parasites preventing their mixing. Whereas most of the dhfr and dhps positions equivalent to those conferring antifolate resistance in P. falciparum and P. vivax were wild type, a new mutation S113C corresponding to the S108 position in pfdhfr was identified in two P. ovale curtisi isolates.ConclusionsThe four human malaria parasite species all occurred sympatrically at the China-Myanmar border. While P. vivax has become the predominant species, the two minor parasite species also occurred at very low prevalence but were often misidentified or missed by conventional microscopy. These minor parasite species displayed low levels of polymorphisms in the msp-1, dhfr and dhps genes.

In this paper, the complex wavelet transform (CWT) was used to process the ultra-high frequency partial discharge (UHF PD) signal in gas insulated switchgear (GIS) at different scales. The trend curves of complex wavelet transform energy entropy (CWT-EE) under different decomposition scale were analyzed, and it was found that the PD feature information mainly distributed in the scales, in which the gradient of CWT-EE is big. Besides, The CWT-EE characteristics and their scales were extracted to the structure characteristic pairs for PD type identification. The recognition results show that the characteristic pair could effectively identify four typical defects in GIS and obviously reduce the feature dimension.

Severely localized deformation within shear bands can occur much more easily in a metal with nanoscale microstructures, such as nanograined and nanolayered materials. Based on atomic-scale observations, here we show that such locally large deformation (the continuous thinning of the layers) within the indentation-induced shear bands of the Cu/Au nanolayers is essentially attributed to the large shear stress component along the interface, which can refresh the capability of the interface to absorb incoming dislocations through unlocking the product of the dislocation-interface reaction. The results have implications for understanding the interface-mediated mechanisms of plastic deformation and for the engineering application of severe plastic deformation processing of metals at nanoscales. DOI: 10.1103/PhysRevLett.110.155502